As a mining method used in a mine, there are known an opencast mining method of mining ore from a ground surface and an underground mining method of mining ore from an underground place. Since an environmental burden needs to be reduced and an ore existing part is located at a deep position, the underground mining method has been more frequently used in recent years. As one of the underground mining methods, for example, a block caving method is known (for example, Patent Literature 1). The block caving method is a method of mining ore by a principle in which the downside of a rock bed or an ore body is undercut and blasted so that a weak rock starts to collapse naturally.